1. Field of the Invention
The present invention relates to a capsule medical device guidance system for guiding a capsule medical device introduced into a subject.
2. Description of the Related Art
Previously, in the field of endoscope, capsule medical devices have appeared which include an imaging function and a wireless communication function inside a capsule-shaped casing formed into a size that can be introduced into the digestive tract of a subject such as a patient. The capsule medical device is swallowed from a mouth of the subject, and then moves in the digestive tract by a peristaltic motion or the like. The capsule medical device sequentially captures images inside an organ of the subject (hereinafter, the image may be referred to as an in-vivo image) and sequentially wirelessly transmits the obtained in-vivo images to a receiving device outside the subject during a period from when the capsule medical device is introduced into the inside of the digestive tract of the subject to when the capsule medical device is discharged to the outside of the subject.
The in-vivo images captured by the capsule medical device are taken into an image display device via the receiving device. The image display device displays the taken in-vivo images as a still image or a moving image. A user such as a doctor or a nurse observes each in-vivo image of the subject displayed on the image display device, and examines the inside of the organ of the subject through the observation of the in-vivo images.
On the other hand, in recent years, a capsule medical device guidance system which guides a capsule medical device inside a subject by a magnetic force (hereinafter referred to as magnetic guidance) is proposed. Generally, in the capsule medical device guidance system, the capsule medical device further includes a permanent magnet inside the capsule-shaped casing, and the image display device displays in real time each in-vivo image sequentially captured by the capsule medical device inside the subject. The capsule medical device guidance system applies a magnetic field to the capsule medical device inside the subject and magnetically guides the capsule medical device inside the subject to a desired position by a magnetic force of the applied magnetic field. While observing the in-vivo image displayed on the image display device, the user operates the magnetic guidance of the capsule medical device by using an operating unit of the capsule medical device guidance system.
As the capsule medical device, there is a capsule endoscope which has a specific gravity capable of floating in a water introduced inside an organ so as to observe the inside of the organ having a relatively large space such as a stomach or a large intestine, and sequentially captures in-vivo images while floating in the water. To intensively examine the inside of an organ having a relatively large space such as a stomach, there is a case in which the subject ingests a water to stretch the inside of the organ (specifically, to stretch folds on the inner wall of the organ) and a capsule endoscope having a specific gravity smaller than that of the water (for example, see International Publication No. 2007/077922). In this case, while the capsule endoscope floats on the water surface with a predetermined posture (for example, a vertical posture in which the center axis in the longitudinal direction of the capsule endoscope is substantially perpendicular to the water surface) inside the organ such as a stomach, the capsule endoscope sequentially captures images of the inside of the organ stretched by the water. The capsule endoscope is moved in desired directions while floating on the water surface inside the organ, and thereby the capsule endoscope can capture a wide range of images inside the organ.